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Adhesive and Process Solutions for LED Packaging Lens
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Adhesives for new lighting concepts LED technology stands for sustainable modern lighting design. Manufacturers make the most of the infi nite design options offered by LEDs to develop versatile, innovative lighting concepts for building technology and lighting engineering in the automotive sector.
Adhesives play a key role in the design and manufacture of LED packages. They are indispensable to the long-lasting function and uniform brightness of the diodes and permit production in the space of a second. The prerequisite however is that the adhesives are precisely tailored to the relevant application area.
DELO has developed special adhesives both for fi rst-level packaging (p. 3), in which the adhesive is located in the immediate vicinity of the LED semiconductor, and for second-level packaging (p. 6), in which the focus is on reliably bonding lenses and housing. In standard tests and implementation by customers worldwide they yield outstanding results and satisfy the high requirements of LED manufacturers.
Manufacturing ever smaller LED packages is one of the requirements. Flip-chip technology (p. 7), and thus the use of conductive adhesives, unlocks new possibilities for manufacturers in this respect.
LED adhesives – your benefits Long-lasting high intensity of the LED and thus high
optical quality Automated, cost-effi cient production possible thanks
to light curing Design creativity thanks to invisible joining, even of
unconventional shapes and materials
Bonding LED packages
Tell our experts what you need and together we will fi nd the right adhesive and process solution for your application fi eld – no matter whether for fi rst-level packaging, second-level packaging, pin sealing or encapsulation. We will be happy to help you turn your product innovations into reality.
www.DELO.show/LED-Bright-Test
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DELO DUALBONDStandard acrylate
Minimal outgassing at +120 °C constant temperature
0 A18
100999897969594939291
0123456789
0 h 24 h 48 h
Storage time
Mas
s re
tent
ion
at +
120
°C [%
]
Out
gass
ing
at +
120
°C [%
]
1 week 2 weeks 4 weeks
3
LED-compatible adhesivesAdhesives and other materials in the immediate vicinity of the LED semiconductor are generally exposed to considerable stressing by high temperatures and LED radiation. In addition, neither the materials themselves, nor potential outgassing elements may be allowed to negatively interact with the LED.
Above all, adhesives based on densely crosslinked epoxies, like DELO DUALBOND adhesives, have proved their worth in these applications. They not only offer
temperature and light resistance, but also low outgassing levels. Another crucial advantage is their special curing mechanism combining light and heat. Light curing permits swift fi xing of the optical components to one another, while heat curing ensures reliable curing even in shadowed areas. And of course, purely light- or heat-curing adhesives are also available.
DELO DUALBOND product featuresLong-lasting high intensity of the LED Minimum outgassing Yellowing-resistant High temperature resistance
Swift processes Easy dispensing and integration into the
production process Optimum curing with DELOLUX LED lamps Fast prefi xing with light possible
Additional qualities Low temperature impact via light curing or
heat curing at low temperatures Refl ow resistance Optically clear products available
Signifi cantly lower outgassing of DELO DUALBOND compared to standard acrylates.
Wide range of halogen-free adhesives according to IEC 61249-2-21FREE
HALOGEN
First level packaging
Dispensing of the adhesive
1
Placement of thelens or refl ector
2a
Curing withlight or heat
31
3
2a
Optional prefi xationwith DELOLUX 50
2b
F F
Temperature [°C]
0 20 40 60 80 100 140 1600
20
40
60
80
100
Com
pre
ssio
n sh
ear
stre
ngth
[%]
in r
elat
ion
to t
he v
alue
at
+23
°C
120
Standard acrylateDELO DUALBOND
High shear strength at increased temperature
A18
Pul
l-of
f for
ce [%
]
20
40
60
80
100
1,000 h+85 °C / 85 % r. h.
10 × reflow 100 cycles–40 °C / +150 °C
Aging resultInitial value
Long-term stability of bond after aging
A18
4
In the lens shear test (see above) DELO DUALBOND shows high bond strength compared to a standard acrylate – especially at high temperatures.
DELO DUALBOND displays high bond strength in standardized reliability tests.
First level packaging tests
Lens shear test
Polycarbonate lens is sheared off the board by a plunger
Test procedureReliable joining is an essential prerequisite when bonding optoelectronic components. Various standardized test procedures can be used to verify whether adhesives comply with the relevant requirements. These tests are an important reference for us to optimally advise our customers on their choice of adhesives.
Among other things, DELO DUALBOND adhesives achieve very good results in humidity storage, temperature shock and repeated refl ow tests, thus ensure long-lasting bonding stability. They also display high shear strength both at low and high temperatures and thus very good bond strength.
Standardacrylate
Standard epoxy
DELO DUALBOND OB
Room temperature
+100 °C
+120 °C
+150 °C
Constant transparency at high temperatures with DELO DUALBOND after 168 h
Time [h]
Inte
nsity
[%]
102030405060708090
100
00 168 336 504 672 840 1008
DELO DUALBONDStandard UV acrylate 1 Standard UV acrylate 2Standard epoxy 1 Standard epoxy 2
Light intensity path in LED Bright Test™
A18
5
LED Bright Test™Adhesives close to the light-emitting diodes are exposed to high stressing due to the heat and radiation given off by the LED. Optical stability may be permanently compromised as a result of yellowing or interaction with decomposition products. DELO DUALBOND adhesives are based on special properties to avoid both these risks.
In the LED Bright Test™ the adhesives display only minimum outgassing and changes in intensity. A further temperature test underscores the adhesive’s optical stability at high temperatures. DELO DUALBOND thus ensures permanently uniform LED brightness.
1,000 h LED Bright Test™
DELO DUALBOND OB:Permanently high intensity
Standard acrylate:Outgassing leads to
fast LED degradation
The outgassing behavior of many standard adhesives reduces LED intensity whereas DELO DUALBOND remains stable.
DELO DUALBOND OB adhesives are stabilized against thermal aging so they remain transparent.
6
Tension-equalizing adhesivesAdhesives used to join lenses, covers, housing and housing components around LED modules are subject to different requirements to fi rst-level packaging. Above all, due to the greater dimensions and different materials used, they need to be profi cient in equalizing any tensions that may arise, for instance, due to changes in temperature. As joins are usually accessible to light, light-curing adhesives in the DELO PHOTOBOND series have proved their worth in this application area.
DELO PHOTOBONDproduct featuresHigh LED intensity Low-outgassing Yellowing-resistant
Permanent bonding Tension-equalizing Humidity-, vibration- and temperature-resistant Universally good adhesion
Processing advantage Light curing in seconds Different viscosity versions
Second level packaging
Dispensing of DELO PHOTOBOND
Placement of the lens on the LED module
Light curing with DELOLUX 80
Precise, fast and automated application of lenses with UV adhesives
1
2
3
Glass / VAPC / AlPMMA / PMMA
0
50
100
150
Initial strength
Excellent universal adhesion after aging
7 days / +80 °C 2 weeks climate changeC
omp
r. sh
ear
stre
ngth
[%]
DE
LO P
HO
TOB
ON
D 4
494
A18
During the aging process compression shear strength increases slightly while at the same time tension-equalizing properties are preserved.
DELO PHOTOBOND 4494
0
50
100
150
200
Initial value
7 days / +80 °C
Flexibility after aging
1,000 h / +85 °C / 85 % r. h.
4 weeks climate change
Elo
ngat
ion
at t
ear
[%]
A18
Even after the aging process DELO PHOTOBOND 4494 retains its fl exibility with elongation at tear greater than 120 %.
7
Bonding a fl ip-chip with anisotropic conductive adhesive
Anisotropic conductive adhesivesIn many LED applications there has been a clear trend towards the use of ever smaller LED chips; edge lengths of less than 200 µm are by no means uncommon. However, conventional contacting via bond wires with pad sizes already of similar dimensions, results in high light yield losses and processing diffi culties.
In this case, fl ip-chip LEDs are the technology of the future. With contacts on the substrate side and anisotropic electrically conductive adhesives they can be bonded directly to the substrate, thus eliminating the need for a further wire bond or refl ow process. This also enables the use of different substrates, including the fl exible fi lms with metallic coating which are indispensable for new lighting concept designs.
DELO MONOPOX AC series adhesives, which are fi lled with conductive particles, were specially developed for bonding fl ip-chips and ensure both permanent contacting and high processing rates.
For many years now DELO has led the market in contacting fl ip-chips for RFID labels in roll-to-roll processing. Drawing on close cooperation with machine builders, DELO can best advise and support customers both in their choice of adhesives and at process level.
for LED packaging
Standard AC adhesiveDELO MONOPOX AC
Constant electrical conductivity
THT [h]
5
4
3
2
1
0
Forw
ard
vol
tage
at
90 m
A (V
)
0 200 400 600 800 1000
A18
DELO MONOPOX AC adhesives ensure constant electrical conductivity.
The data and information provided are based on tests performed under laboratory conditions. Reliable information about the behavior of the product under practical conditions and its suitability for a specific purpose cannot be concluded from this. It is the customer's responsibility to test the suitability of a product for the intended purpose by considering all specific requirements and by applying standards the customer deems suitable (e. g. DIN 2304-1). Type, physical and chemical properties of the materials to be processed with the product, as well as all actual influences occurring during transport, storage, processing and use, may cause deviations in the behavior of the product compared to its behavior under laboratory conditions. All data provided are typical average values or uniquely determined parameters measured under laboratory conditions. The data and information provided are therefore no guarantee for specific product properties or the suitability of the product for a specific purpose. Nothing contained herein shall be construed to indicate the non-existence of any relevant patents or to constitute a permission, encouragement or recommendation to practice any development covered by any patents, without permission of the owner of this patent. All products provided by DELO are subject to DELO’s General Terms of Business. Verbal ancillary agreements are deemed not to exist.
© DELO – This brochure including any and all parts is protected by copyright. Any use not expressly permitted by the Urheberrechtsgesetz (German Copyright Act) shall require DELO’s written consent. This shall apply without limitation to reproductions, duplications, disseminations, adaptations, trans lations and microfilms as well as to the recording, processing, duplication and / or dissemination by electronic means.
CONTACT
Singapore Phone +65 6807 0800 [email protected] www.DELO-adhesives.com/en
Malaysia · Kuala Lumpur Phone +65 6807 0800 [email protected] www.DELO-adhesives.com/en
Headquarters Industrial Adhesives
Germany · Windach / Munich Phone +49 8193 9900-0 [email protected] www.DELO.de
China · Shanghai Phone +86 21 2898 6569 [email protected] www.DELO-adhesives.com/cn
South Korea · Seoul Phone +82 31 450 3038 [email protected] www.DELO-adhesives.com/en
USA · Sudbury, MA Phone +1 978 254 5275 [email protected] www.DELO-adhesives.com/us
Taiwan · Taipei Phone +886 2 6639 8248 [email protected] www.DELO-adhesives.com/cn
Dispensing Curing ConsultingAdhesives
02/18
Headquarters Industrial Adhesives
Germany · Windach / MunichPhone +49 8193 [email protected]
China · ShanghaiPhone +86 21 2898 [email protected]/cn
Japan · YokohamaPhone +81 80 1579 [email protected]/en
SingaporePhone +65 6807 [email protected]/en
Malaysia · Kuala LumpurPhone +65 6807 [email protected]/en
South Korea · SeoulPhone +82 31 450 [email protected]/en
USA · Sudbury, MAPhone +1 978 254 [email protected]/us
Taiwan · TaipeiPhone +886 2 6639 [email protected]/cn
Thailand · BangkokPhone +66 2737 6420 Ext. [email protected]/en
